WASHINGTON — A top aide to Attorney General Janet Reno yesterday said the government will “thoroughly” review whether Amadou Diallo’s civil rights were violated when four cops shot him dead 13 months ago.

“We have not ruled anything out,” said Deputy AG Eric Holder, Reno’s No. 2 aide. “Police misconduct is a very real problem which … undermines citizens’ trust of law enforcement.”

Holder’s promise followed a two-hour meeting with Diallo’s survivors, the Rev. Al Sharpton, members of Congress and others — and a subsequent protest by 2,000 people on the doorstep of the Justice Department.

The protest choked off Pennsylvania Avenue between the FBI building and the Justice Department as protesters turned the wide boulevard into a carnival, with vendors hawking prints, tapes, T-shirts bearing the words “F–Giuliani” and buttons bearing Diallo’s likeness.

Many of the marchers were union workers and others from the New York metropolitan area. Among them were former Mayor David Dinkins and NAACP leader Kweisi Mfume.

Sharpton and event leader Mark Thompson — an NAACP activist and failed repeat contender for a seat on the D.C. Council — claimed the protest was a success and promised more unrest.

“When they shot at Amadou Diallo, they shot at all of us,” shouted Sharpton, who called Diallo — a Guinea immigrant who died on Feb. 4, 1999, in a shower of 41 bullets at the hands of white New York City cops — a “prince of Africa.”

Last week, the four officers who gunned down Diallo were acquitted of state second-degree murder charges, in part because they claimed they thought the victim’s wallet was a pistol.

Rep. Jose Serrano (D-Bronx), who attended yesterday’s meeting, told The Post that fear of the police is rising, creating uneasiness in the community that did not exist before the verdict.

“People in my community tell me they are nervous when they see police,” Serrano said.

Rep. Charles Rangel, the other lawmaker at the meeting, said Holder — who is black — told participants he’s sympathetic to the issue of racial profiling, which is when cops use skin color to identify possible suspects.

“He said he and his family had been subjected to similar types of harassment,” Rangel said. “He was raised in Harlem … he knows what we were talking about.”

Along those lines, a House committee this week approved legislation that would force the government to start collecting data on racial profiling.

Still, even if the Justice Department charges one or more of the cops with a civil-rights violation, convicting them would be next to impossible, experts say.

“The standard … is very high,” Holder conceded.

That’s because prosecutors need to prove that cops set out to deprive Diallo of his civil rights — which last happened in the 1992 police beating of Rodney King in Los Angeles.

Former D.C. Mayor Marion Barry, who served four terms as leader of the city but is best known for his videotaped cocaine bust, urged protesters at the rally not to “give in, give out, or give up.”

“We have to do all we can to stop these mad-dog cops,” shouted Barry, a leader in the 1960s civil-rights protests before he became a politician.